DE112016005843T5 - Method for producing a pin for a mold for a die-casting process - Google Patents

Abstract

A method of manufacturing a pin (46) for a mold (28) includes forming the pin (46) so that it has a substantially uniform initial hardness throughout the structure of the formed pin (46). The formed pin (46) is then machined with a curing process so that the machined pin (46) exhibits a hardness defining a hardness gradient from the initial hardness at a central interior region (56) of the pin (46) to increased surface hardness gradually increases on an outer surface (60) of the pin (46). After machining the pin (46) with the curing process, a coating (64) may be deposited on the outer surface (60) of the pin (46) by a physical vapor deposition process. The coating (64) exhibits a hardness greater than the hardness of the increased surface hardness of the outer surface (60) of the pin (46). The pin (46) may include, for example, a core pin, a push pin, or an ejector pin.

Description

TECHNICAL AREA

The disclosure generally relates to a method of manufacturing a pin for a mold for a die casting process.

BACKGROUND

A die casting mold mainly comprises a die set having a first die half and a second die half. The first die half and the second die half oppose each other and cooperate to form a die defining a casting cavity between the first die half and the second die half. Molten metal is introduced into the casting cavity and, once solidified, forms the casting. The mold may contain one or more different mold pins. The various types of forming pins may include, for example, a core pin, a squeeze pin, or an ejector pin. For example, the mold may include an ejector pin for ejecting a cast article from the mold cavity. Another embodiment of a mold pin may include a core pin for forming a cavity in the casting, e.g. a hole, a hole, a breakthrough, etc. included. The core pin is attached to one of the die halves and extends into the casting cavity. The molten metal flows around the core pin and, as the casting is removed from the mold by the ejector pin when the die set is opened, the core pin leaves the desired cavity in the casting. Moreover, the mold may include a pressure pin for local compaction to eliminate porosity in casts having a complex shape and / or thick wall areas. The mold may be equipped with several different types of mold pins, including, but not limited to, the core pins, the ejector pins, and / or the pressure pins.

The pins used in the mold typically have a useful life that is significantly less than that of the mold. If the pins break or otherwise fail, it will be replaced in the mold. Replacement of the pins requires a significant downtime for the mold and requires the mold to be reheated. Reheating the mold involves draining several shots of a casting material through the mold, which then becomes scrap material.

SUMMARY

What is provided is a method of making a die for a die for a die casting process. The method includes forming the pin from a metal material to define a desired shape. The pin is formed to have a substantially uniform initial hardness throughout the structure of the formed pin. The formed pin is then processed with a curing process so that the machined pin exhibits a hardness that gradually increases from the initial hardness at a central inner portion of the pin to increased surface hardness at an outer surface of the pin.

A method of manufacturing a mold for a die casting process is also provided. The method includes forming a pin of a metal material to define a desired shape. As it is created, the pin includes a substantially uniform initial hardness throughout the structure of the formed pin. The formed pin is then machined with a curing process so that the machined pin exhibits a hardness that defines a hardness gradient that gradually increases from the initial hardness at a central inner portion of the pin to increased surface hardness at an outer surface of the pin. After working the stylus with the curing process, a ceramic coating is deposited on the outer surface of the stylus by a physical vapor deposition process. The ceramic coating exhibits a hardness greater than the hardness of the increased surface hardness of the outer surface of the pin. The pin is then attached to a first die half which cooperates with a second die half to create the mold defining a casting cavity for the die casting process.

Accordingly, the pin is made in a manner that increases the hardness of the pin, thereby increasing its durability and service life without making it excessively brittle.

The above features and advantages and other features and advantages of the present teachings will be readily apparent from the following detailed description of the best modes for carrying out the teachings when taken in conjunction with the accompanying drawings.

list of figures

• 1 Figure 11 is a schematic cross-sectional view of a die casting process showing a mold having a first die half and a second die half.
• 2 Fig. 12 is a schematic cross-sectional view of a pin after the pin is first formed, showing uniform hardness throughout the pin.
• 3 Fig. 12 is a schematic cross-sectional view of the pin after the pin has been processed with a hardening process showing a hardness gradient between a central portion of the pin and an outer surface of the pin.
• 4 FIG. 12 is a schematic cross-sectional view of the pen after a coating has been applied to the processed pen. FIG.
• 5 Figure 3 is an enlarged schematic cross-sectional view of the first die half showing the pen.

DETAILED DESCRIPTION

Those skilled in the art will recognize that terms such as "above," "below," "up," "down," "upper," "lower," etc. are used descriptively throughout the figures, and not limitations on the scope of the disclosure as defined by the appended claims. Moreover, the teachings herein may be described in terms of functional and / or logical block components and / or various processing steps. It should be appreciated that such block components may consist of any number of hardware, software, and / or firmware components configured to perform the particular functions.

Referring to the drawings, wherein like characters indicate like parts throughout the several views, a die-cast system is shown schematically at 20. The die-cast system 20 is used to pour an object 30. While the die-cast system 20 can be used with any suitable material is the die-cast system 20 in particular for casting the article 30 made of a metal such as steel, aluminum or magnesium.

Referring to 1 Contains the die-cast system 20 a die set 22 , The die set 22 includes a first die half 24 and a second die half 26 facing each other around a die 28 to build. One of the first die half 24 and the second die half 26 may be referred to as a movable die, and the other may be referred to as a stationary die. As shown, the first die half is 24 the movable die, and the second die half 26 is the stationary matrix. It should be appreciated, however, that the relative positions of each may be reversed, with the first die half 24 the stationary die is and the second die half 26 the movable die is. The movable die moves into engagement with the stationary die during the die casting process and out of engagement with a stationary die 30 release.

The first die half 24 and the second die half 26 work together to create a casting cavity between them 32 and a sprue cavity 34 define. The casting cavity 32 forms the shape of the object 30 , The runner cavity 34 forms a volume that is utilized to transfer a molten material into the casting cavity 32 initiate. The sprue cavity 34 may be configured in any suitable manner to expedite the molten material into the casting cavity 32 initiate. Accordingly, the shape and orientation of both the casting cavity 32 as well as the sprue cavity 34 of the particular shape of the object to be cast 30 depend.

The die-cast system 20 also includes a melt injection system 36 , The melt injection system 36 is in fluid communication with the gate cavity 34 arranged. The melt injection system 36 serves to melt material in the sprue cavity 34 and thereby into the casting cavity 32 introduce. The melt injection system 36 may be configured in any suitable manner capable of introducing the molten material into the runner cavity 34. For example, the melt injection system 36 a shot or Füllbuchse 38 Shot sleeve), which is arranged in fluid communication with the sprue cavity 34. The filling bush 38 defines a delivery volume and serves to transfer a quantity of molten material through an orifice 40 in the filling socket 38 into the ready volume. A piston 42 is due to the readiness volume of the filling bush 38 movable. The piston 42 serves to melt the material in the standby volume of the filling bushing 38 into the sprue cavity 34 and then force it into the casting cavity 32. The piston 42 can with an actuator 44 such as, but not limited to, a hydraulic ram or other linear actuator 44 be connected and driven by him.

One or both of the first die half 24 and / or the second die half 26 can or can one or more pens 46 contain. The pencils 46 may include, but are not limited to, one of a core pin, a push pin, or an ejector pin. As shown, contains the first die half 24 the pencil 46 , Although only a pen 46 , it should be appreciated that the die set 22 several pens 46 may contain. Moreover, while the exemplary embodiment illustrated in the figures should use the pen 46 Contains the first die half 24 shown attached, be seen that alternatively the pen 46 on the second die half 26 may be appropriate or that the die set 22 several pens 46 can contain, taking some of the pens 46 on the first die half 24 are attached and the rest of the pens 46 on the second die half 26 is appropriate. The pencil 46 is at the first die half 24 attached and carried by her and extends into the casting cavity 32 , As is known in the art, this flows into the casting cavity 32 injected molten material around the pin 46, leaving the pin 46 a cavity 48 in the casting object 30 formed.

A method of making the mold 28 for the die-casting process and, more specifically, a method of making the pen 46 for the form 28 of the die-casting process will be described below. Referring to 2 The method includes forming the pen 46 of a metal material to define a desired shape. Preferably, the pin 46 made of tool steel or high-alloy steel. However, it should be appreciated that the pen 46 of any other material for use inside the mold 28 is suitable, can be formed. The shape of the pin 46 can vary and depends on the desired shape of the cavity 48 in the cast object 30 must be trained. For example, if the pen 46 a cylindrical bore in the cast object 30 training, then the pen 46 be created so that it has a corresponding elongated cylindrical shape. However, it should be appreciated that the shape of the pen 46 may differ from the exemplary cylindrical shape described herein and shown in the figures and may have any other shape.

The pencil 46 is formed so that it covers the entire structure of the formed pen 46 has a substantially uniform initial hardness. In other words, after the initial training of the pen 46 the hardness of the pen 46 the entire length and the entire cross section of the pen 46 through essentially the same. The uniform initial hardness of the pen 46 is the in 2 Cross section indicated by a uniform hatching. The initial hardness of the pen 46 may depend on the specific material that is used to make the pen 46 to form, vary. For example, in one exemplary embodiment, the pen 46 an initial hardness between the range of HRC20 and HRC50 as defined by the Rockwell hardness test.

To the durability of the pen 46 to raise, becomes the created pen 46 processed with a hardening process. Referring to 3 For example, the machined pin 46 has a hardness defining a hardness gradient from the initial hardness at a central interior area 56 of the pen 46 to an increased surface hardness 58 on an outer surface 60 of the pen 46 gradually increases. The initial hardness of the central area 56 is due to the uniform hatching 50 generally stated, whereas the increased hardness of the pen 46 , which defines the hardness gradient, by the hatching 52 is generally indicated with different density. Accordingly, the hardness gradient is an increase in the hardness of the pencil 46 with an increase in the distance from the central area 56 of the pen 46 , The further from the central area 56 of the pen 46 removed, the higher the hardness value. A gradient line 54 represents the hardness gradient and represents an increase in the hardness of the pen 46 from the initial hardness to the increased surface hardness 58 , The hardness gradient structure of the pen 46 dramatically improves the stiffness and fatigue life of the pen 46 during the die casting process, reducing the useful life of the pen 46 is increased.

The central area 56 can be considered a central longitudinal axis 62 of the pen 46 be defined so that the hardness gradient at the central longitudinal axis 62 begins and with an increase in the radial distance from the central longitudinal axis 62 increases. Alternatively, the central area 56 a volume or section of the pen 46 define along the central longitudinal axis 62 of the pen 46 is centrally located. In other words, the central area 56 include a volume defined by a length of the pen 46 and one from the central longitudinal axis 62 of the pen 46 is defined from measured radial distance. If the central area 56 a volume defined as shown in the figures, it should be appreciated that the hardness of the pen 46 the entire central area 56 through the curing process is not significantly affected and the hardness of the pen 46 in the central area 56 at the initial hardness of the pen 46 remains essentially constant. An exemplary embodiment of the pen 46 contains the central area 56 with a maximum volume of between 0% and 30% of the total volume of the pen 46 ,

It should be appreciated that the hardness of the section of the pen 46 that is not part of the central area 56 is increased by the hardening process according to the hardness gradient, so that the outer surface 60 of the pen 46 shows a hardness equal to the increased surface hardness 58 is. In an exemplary embodiment, the increased surface hardness 58 on the outer surface 60 of the pen 46 between the range of HRC40 and HRC55, as defined by the Rockwell hardness test.

The hardening process used to make the pen 46 can process any process that is able to increase the hardness and hardness gradient in the pen 46 to create. For example, the curing process may include, but is not limited to, a nitriding heat treatment process or a massive deformation process.

As known in the art, nitriding is a heat treating process that diffuses nitrogen into the surface of a metal to produce a case hardened surface. The nitrogen can be diffused into the surface of the metal via a gas nitriding process, a salt bath nitriding process or a plasma nitriding process. The gas nitriding process is for use in curing the pen 46 well suited and will be briefly described herein. The gas nitriding process involves heating the workpiece and contacting ammonia (NH ₃ ) gas with the workpiece. When the ammonia comes into contact with the heated workpiece, the ammonia dissociates into nitrogen and hydrogen. The nitrogen then diffuses onto the surface of the material creating a nitride layer. While the gas nitriding process has been briefly described herein, it should be appreciated that other nitriding processes can be used to manipulate the pen 46 to harden and the hardness gradient in the pencil 46 train.

The massive deformation process to harden the pencil 46 and forming the hardness gradient in the pen 46 can include any process, the high pressure on the pen 46 applies to the particles of the pen 46 to compact in the hardness gradients. For example, but not limited to, the massive forming process may include a high energy blasting process or a grinding process. The high-energy blasting process can be an irradiation of the pen 46 with steel balls at high speed to enclose the particles of the pen 46 to condense. The grinding process may include a surface grinding process applied under pressure.

Referring to 4 can if the pin 46 once worked to the hardness of the pen 46 increase and the hardness gradient in the pen 46 to train on the outer surface 60 of the pen 46 a coating 64 be deposited. The coating 64 can be applied in any suitable manner. For example, the coating 64 be applied using a process of physical vapor deposition. The coating 64 shows a hardness greater than the hardness of the increased surface hardness 58 the outer surface 60 of the pen 46 is. The hardness of the coating 64 is by a hatching 66 generally stated. Preferably, the coating closes 64 a ceramic coating 64 one. However, it should be appreciated that the coating 64 may include any other material not specifically disclosed herein which exhibits a hardness greater than the increased surface hardness of the pin 46 is. In an exemplary embodiment, the coating shows 64 a hardness greater than HRC80 as defined by the Rockwell hardness test.

Physical vapor deposition processes include a variety of vacuum deposition processes used to form thin condensation films of a vaporized form of the material of the coating 64 to deposit on the workpiece to the coating 64 to build. The processes of physical vapor deposition are known to those skilled in the art and therefore will not be described in detail herein.

If the pen 46 using the gas nitriding heat treatment process, the pin must 46 be placed in a chamber. The chamber serves to the pin 46 to seal, leaving the pen 46 can be exposed to the ammonia gas. If the pen 46 the coating 64 It is then contemplated that the process of physical vapor deposition with the stylus 46 in the same chamber used to perform the gas nitriding heat treatment process without the pin 46 to remove from the chamber. Unfortunately, the chamber can be used to perform both the gas nitriding heat treatment process and the physical vapor deposition process. This is the formed pin 46 placed in the chamber and edited to the pin 46 to harden and the hardness gradient in the pencil 46 using the gas nitriding heat treatment process, and then, using the physical vapor deposition process, the coating becomes 64 on the pen 46 applied before the pin 46 is removed from the chamber.

Referring to 5 will if the pin 46 once worked to the hardness of the pen 46 and to increase the hardness gradient, and the coating 64 was applied (if desired), then the pin 46 on a respective die half, ie either the first die half 24 or the second die half 26 , appropriate. As noted above, the pen becomes 46 attached to one of the die halves and extends into the casting cavity 32 the form 28 so that the molten material around the pin 46 which, once solidified, can create a cavity 48 in the casting object 30 is created. The pencil 46 may be in any suitable manner on the first die half 24 be attached. Those skilled in the art will be familiar with the processes used to make a pen 46 to be attached to a die half. Accordingly, the specific process for attaching the pen 46 on the first die half 24 not described in detail herein.

The detailed description and drawings or figures support and describe the disclosure; but the scope of the disclosure is defined only by the claims. Although some of the best modes and other embodiments for carrying out the claimed teachings have been described in detail, there are several alternative designs and embodiments for practicing the disclosure defined in the appended claims.

Claims (20)

A method of making a die for a die for a die casting process, the method comprising: Forming the pin from a metal material to define a desired shape such that the pin has a substantially uniform initial hardness throughout the structure of the formed pin; and Machining the formed pin with a curing process such that the machined pin exhibits a hardness that gradually increases from the initial hardness at a central interior portion of the pin to increased surface hardness at an outer surface of the pin. Method according to Claim 1 further comprising depositing a coating on the outer surface of the pin with a physical vapor deposition process, the coating exhibiting a hardness greater than the hardness of the increased surface hardness of the outer surface of the pin. Method according to Claim 2 wherein the coating is a ceramic coating. Method according to Claim 2 wherein the coating exhibits a hardness greater than HRC80 as defined by the Rockwell hardness test. Method according to Claim 1 wherein the initial hardness of the pin is between the range of HRC20 and HRC50 as defined by the Rockwell hardness test. Method according to Claim 5 wherein the increased surface hardness on the outer surface of the pin is between the range of HRC40 and HRC55 as defined by the Rockwell hardness test. Method according to Claim 1 wherein the central area of the pen comprises a maximum volume of between 0% and 30% of a total volume of the pen. Method according to Claim 1 wherein machining of the formed pin with the curing process is further defined as machining the formed pin with a nitriding heat treatment process. Method according to Claim 8 further comprising depositing a coating on the outer surface of the pin with a physical vapor deposition process after the nitriding heat treatment process, wherein the coating exhibits a hardness greater than the hardness of the increased surface hardness of the outer surface of the pin. Method according to Claim 9 further comprising placing the formed pin in a chamber prior to machining the formed pin with the nitriding heat treatment process. Method according to Claim 10 wherein the steps of processing the formed pin with the nitriding heat treatment process and depositing the coating on the outer surface of the pin after the nitriding heat treatment process are both performed with the pin in the chamber. Method according to Claim 1 wherein machining of the formed pin with the hardening process is further defined as machining the formed pin with a massive deformation process. Method according to Claim 12 wherein the massive deformation process comprises either a high energy blasting process or a grinding process. Method according to Claim 12 further comprising depositing a coating on the outer surface of the pin with a physical vapor deposition process after the massive deformation process, wherein the coating exhibits a hardness greater than the hardness of the increased surface hardness of the outer surface of the pin. A method of manufacturing a mold for a die casting process, the method comprising: forming a pin of a metal material to define a desired shape so that the Pin has a substantially uniform initial hardness throughout the structure of the formed pin; Machining the formed pin with a curing process so that the machined pin exhibits a hardness that defines a hardness gradient that gradually increases from the initial hardness at a central inner portion of the pin to an increased surface hardness at an outer surface of the pin; Depositing a ceramic coating on the outer surface of the pin by a process of physical vapor deposition after machining the pin with the curing process, the ceramic coating exhibiting a hardness greater than the hardness of the increased surface hardness of the outer surface of the pin; and attaching the pin to a first die half which cooperates with a second die half to form the die defining a casting cavity for the die casting process. Method according to Claim 15 wherein: the initial hardness of the central portion of the pin is between the range of HRC20 and HRC50 as defined by the Rockwell endurance test; the increased surface hardness on the outer surface of the pin is between the range of HRC40 and HRC55 as defined by the Rockwell hardness test; and the ceramic coating exhibits a hardness greater than HRC80 as defined by the Rockwell hardness test. Method according to Claim 16 wherein the central area of the pen comprises a maximum volume of between 0% and 30% of a total volume of the pen. Method according to Claim 17 wherein machining of the formed pin with the curing process is further defined as machining the formed pin with a nitriding heat treatment process. Method according to Claim 18 wherein the steps of machining the formed pin with the nitriding heat treatment process and depositing the coating on the outer surface of the pin after the nitriding heat treatment process are both performed sequentially with the pin arranged in a single chamber. Method according to Claim 17 wherein machining the formed pin with the hardening process is further defined as machining the formed pin with a massive deformation process, wherein the massive deformation process comprises either a high energy blasting process or a grinding process.

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